Process for beneficiating potash spar



United States Patent Ofiflce 3,073,443 Patented Jan. 15, '1963 3,073,443 PROCESS FOR BENEFICIATENG PUTASH PAR Robert E. Snow, Lakeland, Fla., assignor to International Minerals & Chemical Corporation, a corporation of New York No Drawing. Filed Sept. 23, 1960, Ser. No. 57,897 18 (Ilaims. (Cl. 209-9) The present invention generally relates to a process for the beneficiation of ores. More particularly, this invention relatesto the beneficiation of feldspathic rock materials and minerals. Still more particularly, it relates to a process for the preparation of potash spar. concentrates and soda spar concentrates from mixtures of potash spar and soda spar. Specifically, the present invention relates to the recovery of potash spar concentrates and soda spar concentrates from flotation concentrates obtained in froth flotation processes for the recovery of feldspar, which flotation concentrates contain potash spar and soda spar.

Feldspar is the name of a group of minerals, specifically aluminosilicates of potassium, sodium, calcium, and rarely barium. The aluminosilicate of potassium or potash spar, and the aluminosilicate of sodium or soda spar are commercially important. They are used as a ceramic fluxing agent, a source of alkalies and alumina, and as an ingredient in glass manufacture.

Theoretically pure feldspars of any type are not found in commercial quantities. The best potash spars usually contain a small percentage of soda spar and, similarly, the best soda spars usually contain a small percentage of potash spar. For some uses of feldspar, a particularly high ratio of potash spar to soda spar is desirable and for other uses of feldspar a particularly high ratio of soda spar to potash spar is desirable. For example, for electrical and dental porcelain uses, a high potash spar is needed.

Feldspar has for many-years been beneficiated by milling methods utilizing magnetic separations. Froth flotation beneficiation of feldspar is also employed commercially. Electrostatic beneficiation of feldspar is also of economic importance. One method of electro'statically beneficiating feldspathic ore is described in Lawver, United States Patent No. 2,805,771. Using the electrostatic method described in the Lawver patent-it is possible to separate chemically different feldspars, i.e., soda spar from potash spar, spars rich in alkali metal component, and the like.

,In the froth flotation process for beneficiating feldspathic ore, the comminuted feldspathic ore is reagentized with cationic flotation reagents. Flotation concentrates obtained in froth flotation processes may be upgraded electrostatically by the method described in the Lawver patent. Further, using the method described in the Lawver patent potash spar may be substantially separated from soda spar in flotation concentrates so as to separately prepare a high potash spar concentrate and a high soda spar concentrate. The present invention is directed to the problem of improving the beneficiation of feldspar flotation concentrates.

It is an object of the present invention to provide a process for the beneficiation of feldspathic ores.

It is another object of the present invention to provide a process for the beneficiation of feldspar flotation concentrates. a I It is a further object of the present invention to provide a process for the beneficiation of feldspar flotation con-l centrates containing soda spar and potash spar.

. It is an additional object of the present inventionvto provide 'a process for preparing a high potash spar concentrate. p

It is still a further object of the present invention to provide a process for preparing a high soda spar concentrate.

It is a specific object of the present invention to treat a feldspar flotation concentrate so as to substantially increase the separation of potash spar from soda spar when the flotation concentrate is subjected to an electrostatic separation operation.

These another objects of the invention will be apparent to those skilled in the art from the description of the invention.

In accordance with the present invention, it has been discovered that eminently satisfactory beneficiation of feldspar flotation concentrates can be achieved electrostaticallyby means of a series of critical and interdependent process steps. 7

Generally described, the present invention comprises treating a feldspar concentrate with a halogen-containing reagent, heating the treated concentrate, inducing the heated concentrate to accept differential electrical charges, and subjecting the charged concentrate to an electrostatic separation.

When beneficiating a feldspathic ore according to flotation procedures, the ore as received from the mine is, inter alia, comminuted to economical liberation sofas to substantially liberate the feldspar particles from the gangue, The comminuted ore is subsequently subjected to a froth flotation operation with cationic reagents such as long chain aliphatic amine acid addition'salts. The frothfloat product is high in feldspar content.

As hereinbefore set forth, this froth float feldspar concentrate may be beneficiated according to the method set forth in Lawver U.S. Patent No. 2,805,771. However, when the feldspar concentrate is first treated with a halogen-containing reagent in accordance with the present invention, a markedly improved beneficiationis obtained. Further, a separation of potash spar from soda spar may be obtained in the subsequent electrostatic separation step.

7 The feldspar ore charged to the forth flotation process is usually comminuted to an extent such that further comminution prior to the electrostatic separation may not be necessary. The eiiiciency of the electrostaticseparation of i the treated flotation concentrate is to a'degree dependent upon the particle size of the comminuted ore. Generally, the particles should be smaller than 4mesh. The most satisfactory particle size range for feldspar beneficiation, from an economic standpoint, is where approximately of the particles are of a size between about 8 mesh} and about 200 mesh, most of the particles preferably being' between about 20' mesh and about 100 mesh size. Where the flotation concentrate is of a size that it falls substantially within the range of from about 8 mesh to about 200 mesh, further comminution and/or sizing may not be 5: necessary; however, further comminution and/or sizing may be performed if necessary or desirable.

known types of flotation machines.

amine type. Preferred amine-type reagents are ;jlong chain aliphatic amines, their addition salts, and ,deriva tives thereof. Thereagent is usually-modified by the addition of fluosilicic acidandl or hydrofluoric acid and/or I an alkali metal fluoride.- An oiling agent or extendenand alfrothingagent are also usually added to'the oreipulpt The cationic reagent-has a selective aflinity for are feldspar minerals. and floats the feldspar minerals duringthe flotation operation.v 1 As "hereinbefore set forth, .these' cationic flotation concentrates may be upgraded in accordance with the electroi 3 static process set forth in Lawver Patent No. 2,805,771; however, it has now been determined that the electrostatic beneficiation is improved when the cationic flotation concentrate is treated with a halogen-containing reagent prior to the electrostatic Separation.

In accordance with this invention, the feldspar flotation concentrate, while still containing the cationic flotation reagent, is treated with a halogen-containing reagent. The halogen-containing reagent preferably makes maximum contact with the surface of the particles in the feldspar concentrate and, accordingly, the method of treatment is one which insures good contact. A preferred method is is treat the cationic feldspar flotation concentrate with the halogen-containing reagent in an aqueous slurry. An aqueous solution containing a halogen and/or a halogen compound may also be sprayed onto the feldspar flotation concentrate. Mixing or scrubbing the feldspar flotation concentrate and halogen and/or halogen compound to gether in an aqueous slurry is, however, preferred since good contact is readily obtained and this method has produced good results. The mixing or scrubbing is preferably for a period of at least one minute and is usually for less than one hour. A- longer period may, however, be used if desired.

Any suitable halogen-containing reagent may be used in the process and includes halogens and their compounds. f the halogens, bromine, iodine and chlorine are preferred. As hereinbefore set forth, the feldspar concentrate is preferably scrubbed or mixed in an aqueous solution. Therefore, the feldspar concentrate may be in an aqueous slurry and the halogen added thereto; or the feldspar concentrate may be relatively dry and an aqueous solution of the halogen mixed therewith; or the feldspar concentrated may be in an aqueous slurry and a solution of the halogen, which may be an aqueous solution, alcohol solution, or other solution of the halogen, mixed therewith. Of the halogen compounds, the halogen oxyacids, and salts which provide a halogen and/or hypohalite and/ or halite ions when in aqueous solution are preferred, especially the alkali metal salts; however, alkalineearth metal salts are also useful. Examples of halogen oxy' acids are hypochlorous acid, HClO, perchloric acid, H610 chlorous acid, HCIO chloric acid, HClO and the corresponding bromine and iodine acids. Specifically preferred halogen salts are bleaching powder (CaCl(ClO)), sodium chlorite, potassium chlorite, sodium chlorate, potassium chlorate, sodium hypochlorite, potassium hypochlorite, sodium perchlorate, potassium perchlorate, as well as the corresponding bromine and iodine salts. The halate and perhalate saltsare used in an aqueous solution to which an acid providing a halide ion is added so as to give a halogen and/or a hypohalite' acid in the aqueous solution used to treat the feldspar flotation concentrate. The halogen-containing reagent is used in an amount to provide at least 0.01 and preferably from about 0.01 to about 50 lbs. of the halogen per ton of solids treated and more preferably to provide from about 0.50 to about 40 lbs. of the halogen per ton of solids treated. The amount of the halogen-containing reagent is calculated as elemental halogen, although, of course, the halogen is present as the halogen element and/ or as a halogen compound.

The aqueous slurry of feldspar flotation concentrate and halogen-containing material may be neutral, acidic,-or basic; however, it is preferred that the pH of'tlie aqueous slurry of feldspar concentrate and halogen-containingreagent be 7.0 or above, and preferably Within the range of from about 7.0 to about 12.0, that is, the aqueous slurry is preferably basic.

After treatment of the feldspar flotation concentrate with the halogen-containing reagen, the treated flotation feldspar concentrate is preferably thoroughly washed anddewateredl The thoroughly washed and dewatered feldspar concentrate is then dried and subjected to an electrostatic separation operation. A preferred electrostaticsep- 4 aration operation is that described by Lawver in US. Patent 2,805,771.

The exact reason why the treatment of the feldspar flotation concentrate containing the cationic reagent with the halogen-containing reagent prior to the electrostatic separation is beneficial is not definitely known, and it is not intended to limit the invention to any theory. However, it is believed that when the cationic reagent is added to the feldspathic material, the ions of the flotation re agent attach themselves at the sites on the particles which would assume electrical charges when the material is subjected to charging, and either prevent proper charging or neutralize the electrical charges. Investigations have indicated that the halogen-containing reagent reacts with and removes the cationic flotation reagent on the surfaces of the feldspar particles thus enabling proper electrical charging of the feldspar particles, prior to entry into the electrostatic field, to be more readily effected.

As hereinbefore set forth, the electrostatic separation is to a degree dependent upon the size of the particles and a preferred size range is from about 8 mesh to about 200 mesh. If the particles are not within this size range, it is preferred that the flotation concentrate be comminuted and/or sized. The comminution may be performed at any suitable stage, that is before or after treatment with the halogen-containing reagent; however, it is preferred that any comminution and/or sizing be performed before the treatment with the halogen-containing reagent.

The feldspar flotation concentrate, after being treated with the halogen-containing reagent is then further treated to develop electrical charges upon the ore particles. Before the concentrate is treated to induce the concentrate particles to accept differential electrical charges, the concentrate is preferably dried to substantially eliminate conductivity of films on the surface of the particles. When the drying is effected by heating the concentrate, a wide range of temperatures may be used, depending upon the degree of separation desired in the electrostatic separation and the nature of the feed. The concentrate is desirably heated to dryness at a temperature of at least 150 F. and maintained at a temperature of at least 150 F. during the charging and up to the point of introduction as free falling bodiesi'nto the electrostatic field. Higher temperatures which do not deleteriously affect the mineral can be employed and in many instances are required in order to satisfactorily prepare the particle surfaces for optimum separations. In general, temperatures of between about 150 F. and 750 F. produce the desired results. Heating is generally carried on to a temperature above 300 F. and in a preferred range of from about 500 F. to about 650 F. The effect of this heating isevidenced by the increase in the K 0 value of the concentrate and also the improved recovery of K 0 values in the concentrate when a comparison is made between the separations accomplished after heating to the preferred range as compared to that of, for example, 200 F. Concentrates vary in composition and the optimum heating range may vary considerably, but in general will not be outside the heating range of 150 F. to 750 F. When heating at a temperature in the lower end of this range a longer period of time is usually required. The time of heating is generally within the range of from about one minute to about two hours.

Following the heat treatment the feed material is cooled to a temperature in the range of from about F. to about 450 F. andpreferably of from about 250 F. to about 350 F. Separation of heat treated material when cooled so as to'be substantially cold, howeverycan be effected.

In order to accomplish electrostatic separation either by the free fall method or by so-called conductivity sepmust be differentially electrified before passage through the electrostatic field, i.e., particles of gangue minerals,

when the for example, must carry an electrical charge of different character or of different magnitude from that of the feldspar minerals. The differential charge may be acquired, for example, by rupture of an electrical double layer by mechanical means, as, for example, from interparticle contact and separation, or by transfer of electrons from a source external to the particles, or any combination of these methods.

Charging, in accordance with the invention, is predominantly attained through the medium of contact electrification. Contact electrification results from the movement of matter in response to such stimuli as differences in escape rate of positive or negative charges, or transfer of electrons or'ions across an interface due to differences in energy levels and the like. It has been determined that real crystals never attain the static perfection of an ideal crystal lattice and that a real crystal may have distorted surfaces, displaced ions or atoms, interstitialsites and surface sites, and charge displacement due to separated anioncation pairs of abnormal ionized atoms and trapped electrons. It is postulated that these traps are capable of acting as donors and acceptors of electrons and frequently it is these traps that are probably the controlling influences in contact electrification of minerals.

Particles of dissimilar materials, if the surfaces thereof do not exhibit differential electrification upon subjection to contact electrification operations, such as agitation,

I electrostatic field.

often can be caused to exhibit differential electrification by thermal, chemical, or electromagnetic methods.

Basically, the desired contact electrification depends on temperature, impurity content, and mechanical history of the various surfaces involved. Therefore, it is preferable to determine the precise conditions requisite to optimum selective charging. Under certain conditions the surfaces of the mineral species are such that it is possible to electrify by mineral-metal contact electrification. For example, if such contact causes high electrification with one mineral species, a selective separation is possible. plete discussion of charging mechanisms may be found in Fraas et al., Industrial and Engineering Chemistry, volume 32, pages 601-60211940).

It has been discovered that greatly improved differential charging of the particles is accomplished in accordance with the invention by essentially particle-toparticl'e contact while the dry comminuted material ismaintainedat a A more com- 6 ceptable beneficiation. Therefore, the material just prior to its entry into the electrostatic field should be at a temperature in the range from about 100 F. to about 450 F. and preferebaly from about 250 F. to about 350 F.; however, as hereinbefore set forth, higher or lower temperatures may be used. Entry of the granular material into the electrostatic field at temperatures within this range is preferred since numerous observations have shown that the best separations are achieved in this temperature range. Where mineral particles are subjected to a series of electrostatic separations, the feed to subsequent stages often exhibits progressively reduced response to the It is believed that this reduced response may be due to loss or leakage of charges from the granular particles or coating of the charged granular particles with fines. Such weak-responding concentrates may in one form of treatment be restored or induced to activity by passage through an impactor to create new' surfaces and again recharging by frictional or other methods that give rise to differential electrification, which recharging may include a reheating in accordance with the treatment hereinabove described.

are to be avoided. In general, it is preferred to operate with a total impressed difference of potential in therange of about 30,000 volts to about 250,000 volts. This voltage should -be maintained by means of a direct current potential source substantially free of ripple. A steady supply of direct current maybe obtained by the use of such equipment as a rectified radio frequency power supply. p r f In order to give a fuller understanding of the invention, but with no intention to be limited thereto, the following specific examples are given:

ing the charging operation." Where the: charging of the s particles is accomplished essentially by particle-to-particle in a number of ways, suchas by tumbling the particles down an elongated chute in such quantity that contact between the particles and the chute is at a' minimum. Alternatively, the comminuted mineral, while maintained at a proper temperature, may be delivered from the drying apparatus to theelectrostatic separator by means of a vibrating trough. At high throughput the great prepon-- derance of charging is engendered by particle-to-particle contact rather than by contact of the particles with the trough. Suitable charging also may be obtained by agita I tion of the heated, c'ornminuted material.

' Theinitial beneficiation ofthe mineral feed is effected by passing the comminuted material as freely falling bodies through an external electrostatic field. It is desirable to the satisfactory operation of the processthatthe'particulate minerals, when delivered toand'dropped iri'to the electro-' static field, be dry in order to achieve commercially ac- Potash spar 41 T Soda spar' 54 Quartz, 355:,

, EXAMPLE I A sample of feldspar ore mined in the vicinity of Kona, North, Carolina, was comminutedand classified to produce a substantially 20 +200 mesh fraction. In the processing of this ore to recover the feldspana froth flo- V 'tation operation was utilized. The froth fiotationoperation was conducted in the presence of a cationic flotation reagent composition comprising hydrofluoric acid, an-

The 1 hydro fiuoric'acid was added as a 5% aqueous solution and was added in-the amount of about 4 lbs. of HF peri ton of ore treated. The cationic collector used was pre- 'pared by emulsifying a mixture of primary tallow oil amine acetates sold under the trade name"Armac T,. de-

amine-type collector and an alcohol-type frother.

hydroabietylamine acetate, and No. 2 fuel oil, in the ratio of about 1:1:2, with water to obtain a 5% solution. This collector was used in the amount of about 2.5 lb. of reagent per ton of ore. treated. The frother was methyl isobutyl carbinol and was used in the amount of about 0.6 lb. per ton of ore treated.

The mineral composition of a feldspar flotation conceritrate obtained in a froth flotationprocess substantially as described was as follows: J

The-sample assayed 5.6% K50 and 6.2% Na OL" Percent? Test A A 1000 gram portion of the concentrate was scrubbed with water at 50% solids content for 5 minutes. The scrubbed concentrate was dewatered by decantation and heated to 560 F. in a shallow pan for 30 minutes. The heated concentrate was then cooled to 300 F., delivered to a feed hopper, and cascaded downwardly through a vibrating metal trough which was grounded to the earth by an electrical conductor. Material in the trough passed as a layer of A" to /2 depth. The material was thereby differentially charged and was then permitted to fall freely between electrodes at a rate of approximately 500 pounds per hour per foot of horizontal electrode width. The electrodes consisted of two spaced rows of 3 diameter aluminum tubes arranged with approximately 1" of space between the tubes. The rows of electrodes were approximately 10" apart. The impressed voltage across the electrodes was 75,000 volts D.C.

Below the electrodes, seven catch pans were properly arranged to catch the separate ore fractions. The electrostatic separation results are shown below in Table 1A.

The chemical analyses of the various pan products shows that some separation of the potash spar from the soda spar was obtained, however, a greater than 10% K product was not produced.

Test 1B A second 1000 gm. portion of the feldspar flotation concentrate was scrubbed for 5 minutes at 50% solids with 4 pounds per ton of bromine added to the pulp as a saturated bromine water solution. The scrubbed concentrate was washed, dewatered by decantation, and heated to 560 F. in a shallow pan for 30 minutes. The heated concentrate was cooled to 300 F. and subjected to an electrostatic separation substantially the same as described in Test 1A. The results of the electrostatic separation are given below in Table 1B.

Another 1000 gm. portion of the feldspar flotation con centrate was scrubbed for 5 minutes .at 50% solids with i 4 pounds per ton of iodine added as'a 10% solution in methanol, washed and dewatered by decantation, heated in a shallow pan at 560 F. for 30 minutes, cooled to 300 F., and subjected to an electrostatic separation substantially the same as utilized in Example I. Electrostatic separation results were as shown in the following Table 2.

TABLE 2 Wt. percent K20 Wt. percent cedure outlined in Example III.

static separation are shown below in Table 4:

Composite EXAMPLE III Six 1500 gm. portions of the flotation concentrate were individually scrubbed at 40% solids with 40 pounds per ton of sodium hypochlorite, added as commercial Clorox solution, for a 5 minute period. Each scrubbed sample was washed and dewatered by decantation, pan heated for 30 minutes at 580 F., cooled to 300 F., and subjected to substantially the same electrostatic separation described in Example I in order to determine thegeneral reproducibility of the process with respect to producing a greater than 10% K 0 potash spar concentrate. The following Tabel 3 illustrates that sodium hypochlorite pretreatment enabled consistant electrostatic separation of a greater than 10% K20 potasth spar concentrate.

TABLE 3 Wt. percent percent Wt percent Wt K20 EXAMPLE IV Another 1500 gm. sample of North Carolina feldspar flotation concentrate, difierent from the sample used in Examples I, II, and III, .was subjected to the same pro- Results of the electro- As shown in Table 4', a 10% K 0 potash spar wasobtained from this ore using Clorox pretreatment. no Clorox was used with this sample, pans 6 plus 7 assayed only 8.6% K 0.

The description of the invention utilized specific referenceto certain process details, however, it is to be understood that such details are illustrative only and not by way of limitation. Other modifications and equivalents of the invention will be apparent to those skilled in the art from the foregoing description.

Having now fully described and illustrated the invention, what is desired to be secured and claimed by Letters Patent is set-forth in the appended claims.

When

acrea e I claim:

1. A process for beneficiating potash spar in a feldspar flotation concentrate obtained as a float product in a cationic flotation operation which comprises treating said feldspar flotation concentrate still containing cationic flotation reagent with a halogen-containing reagent, heating the treated concentrate, inducing the heated concentrate by contact-electrification to accept differential electrical charges, subjecting the charged concentrate to an electrostatic separation, and recovering a concentrate fraction of increased potash spar concentration and reduced soda spar concentration.

2. The process of claim 1 wherein treatment of said feldspar flotation concentrate with a halogen-containing reagent comprises treatment with an aqueous solution of bromine.

3. The process of claim 1 wherein treatment of said feldspar flotation concentrate with a halogen-containing reagent comprises treatment with an aqueous solution of chlorine.

4. The process of claim 1 wherein treatment of said feldspar flotation concentrate with a halogen-containing reagent comprises treatment with a solution of iodine.

5. A process for beneficiating potash spar in a feldspar flotation concentrate obtained as a float product in a cationic flotation operation which comprises treating said feldspar flotation concentrate still containing cationic flotation reagent with an aqueous solution of sodium hypochlorite, heating the treated concentrate, inducing the heated concentrate by contact electrification to accept difierential electrical charges, subjecting the charged concentrate to an electrostatic separation, and recovering a concentrate fraction of increased potash spar concentration and reduced soda spar concentration.

6. A process for beneficiating potash spar in a feldspar flotation concentrate obtained as a float product in a cationic flotation operation which comprises treating said feldspar flotation concentrate still containing cationic flotation reagent with an aqueous solution of CaC1(ClO), heating the treated concentrate, inducing the heated concentrate by contact electrification to accept differential electrical charges, subjecting the charged concentrate to an electrostatic separation, and recovering a concentrate fraction of increased potash spar concentration and reduced soda spar concentration.

7. A process for beneficiating potash spar in a feldspar flotation concentrate obtained as a float product in a cationic flotation operation using a cationic flotation reagent which comprises aqueous slurrying said feldspar flotation concentrate, while still containing cationic flotation reagent, with a halogen-containing material selected from the group consisting of the halogens, alkali metal salts providing halogen in aqueous solution, alkali metal salts providing halite ion in aqueous solution, alkali metal salts providing hypohalite ion in aqueous solution, alkaline earth metal salts providing halogen in aqueous solution, alkaline earth metal salts providing halite ion in aqueous solution, alkaline earth metal providing hypohalite ion in aqueous solution, halogen oxyacids and mixtures thereof, drying and heating the treated concentrate, inducing the heated concentrate by contact electrification to accept l0 differential electrical charges, subjecting the charged concentrate to an electrostatic separation, and recovering a concentrate fraction of increased potash spar concentration and reduced soda spar concentration.

8. The process of claim 7 wherein the halogen-containing material provides at least about 0.01 pound of halogen per ton of feldspar flotation concentrate.

9. The process of claim 7 wherein the halogen-containing material provides from about 0.01 to about 50 lbs. of halogen per ton of feldspar flotation concentrate.

10. The process of claim 7 wherein the halogen-containing material provides from about 0.5 to about 40 lbs. of halogen per ton of feldspar flotation concentrate.

11. The process of claim 8 wherein the aqueousslurry of feldspar flotation reagent and halogen-containing material has a pH above about 7.0.

12. The process of claim 8 wherein the treated concentrate isheated to a temperature within the range of from about 150 F. to about 750 F.

13. The process of claim 8 wherein the treated concentrate is induced to accept electrical charges while at a temperature within the range of from about F. to about 450 F.

14. A process for beneficiating potash spar in a feldspar flotation concentrate obtained. as a float product in a cationic flotation operation using acationic flotation reagent which comprises water slurrying said feldspar flotation concentrate, while still containing cationic flotation reagent, with a halogen-containing material, drying and heating the treated concentrate to a temperature within the range of from about F. to about 750 F., inducing the heated concentrate by contact electrification to accept different electrical charges while at a temperature within the range of from about 100 F. to about 450 F., subjecting the charged concentrate while at a temperature within the range of from about 100 F. to about 450 F. to an electrostatic separation, and recovering a concentrate fraction of increased potash spar concentration and reduced soda spar concentration.

15. The process of claim 14 wherein treatment of said feldspar flotation concentrate with a halogen-containing material comprises treatment with an aqueous solution of bromine.

16. The process of claim 14 wherein treatment of said feldspar flotation concentrate with a halogen-containing material comprises treatment with an aqueous solution of chlorine.

17. The process of claim 14 wherein treatment of said feldspar flotation concentrate with" a halogen-containing material comprises treatment with an aqueous solution of chlorine.

18. The process of claim 14 wherein treatment of said feldspar flotation concentrate with a halogen-containing material comprises treatment with an aqueous solution of sodium hypochlorite.

References Cited in the file of this patent UNITED STATES PATENTS 2,090,418 Johnson Aug. 17, 1937 2,245,200 Johnson June 10, 1941 2,805,771 Lawver Sept. 10, 1957 

1. A PROCESS FOR BENEFICIATING POTASH SPAR IN A FELDSPAR FLOTATION CONCENTRATE OBTAINED AS A FLOAT PRODUCT IN A CATIONIC FLOTATION OPERATION WHICH COMPRISES TREATING SAID FELDSPAR FLOTATION CONCENTRATE STILL CONTAINING CATIONIC FLOTATION REAGENT WITH A HALOGEN-CONTAINING REAGENT, HEATING THE TREATED CONCENTRATE, INDUCING THE HEATED CONCENTRATE BY CONTACT-ELECTRIFICATION TO ACCEPT DIFFERENTIAL ELECTRICAL CHARGES, SUBJECTING THE CHARGED CONCENTRATE TO AN ELECTROSTATIC SEPARATION, AND RECOVERING A CONCENTRATE FRACTION OF INCREASED POTASH SPAR CONCENTRATION AND REDUCED SODA SPAR CONCENTRATION. 